Circular saws of the aforementioned type are in various embodiments in the related art.
German patent document DE 295 10 061 U1, for example, discusses a hand-held circular saw having a housing on which a base plate having a workpiece support is pivotably mounted. A saw blade together with the associated motor unit is accommodated in the housing in a known manner, it being possible with the aid of the motor unit to rotatingly drive the saw blade about a rotational axis which does not rotate. The saw blade may be moved through the base plate in such a way that the saw blade projects from the workpiece support surface in order to engage with a workpiece situated on the workpiece support surface. At the rear region of the housing, a splitting wedge support is positioned which is fixedly mounted with respect to the rotational axis of the saw blade, and which together with this rotational axis may be moved up and down and swiveled.
A splitting wedge which is normally made of spring steel sheet metal is detachably fastened to the splitting wedge support with the aid of screws, and extends along a region of the outer periphery of the saw blade. While a workpiece is being cut, the splitting wedge engages with the incision provided in the workpiece, so that the splitting wedge guides the hand-held circular saw. In addition, the splitting wedge prevents the workpiece from tilting or recoiling, and shields a portion of the saw blade for protection of the operator. Furthermore, a retractable blade guard which encloses the upper region of the saw blade is mounted on the splitting wedge, and prevents the operator from coming into contact with this upper region of the saw blade. The retractable blade guard also provides protection from flying chips. The retractable blade guard may also be provided with a device for vacuum removal of the chips.
Table circular saws which have a saw table are also known. The saw table includes a workpiece support surface on which a workpiece may be situated. A saw blade together with the associated motor unit is situated beneath the saw table. The saw blade may be moved up and down through the saw table so that the saw blade may be situated to project from the workpiece support surface in order to engage with a workpiece positioned on the workpiece support surface. A splitting wedge is detachably mounted on a splitting wedge support with the aid of screws or the like; similarly as for the previously described hand-held circular saw, the splitting wedge support is fixedly mounted with respect to the rotational axis of the saw blade, and together with the saw blade may be moved up and down and swiveled. The splitting wedge extends along an outer periphery region of the saw blade, and during machining of a workpiece engages with the incision provided in the workpiece. This splitting wedge is also used for guiding the workpiece and protecting the operator.
If work operations are to be carried out using circular saws of the type described above which are impaired by the presence of the splitting wedge, such as an inset cut, for example, in which the saw blade does not cut into the workpiece starting from the edge of the workpiece, but instead penetrates the workpiece surface in the center, the splitting wedge must be uninstalled before such work operations are carried out. The splitting wedge may be reinstalled after such work operations are completed.
However, uninstalling and installing the splitting wedge is time-consuming and therefore costly, which is not desirable in practice.
Furthermore, handling the circular saws during the period of time in which no splitting wedge is provided is extremely hazardous. An in-house study by the applicant has shown that the odds ratio (OR) value for conventional work operations carried out using hand-held and table circular saws is approximately 1.84. The OR value is obtained by taking the ratio of the relative number of work accidents which occur for a given work operation to the relative amount of time that the work operation requires compared to all work operations; for an OR value greater than 1 a work operation is classified as an above-average hazard. For carrying out an inset cut, an OR value as high as approximately 25 has been determined. The occurrence of an extraordinarily large number of accidents during this work step may be explained, at least in part, by the fact that in this case the splitting wedge must be removed. As a result, in normal practice the operator frequently does not immediately reinstall the splitting wedge on the circular saw after completion of such a work operation. Instead, further work operations which could be carried out with the splitting wedge installed are intentionally or unintentionally performed on the workpiece before the splitting wedge is reinstalled. However, for safety reasons it would be desirable to minimize the period of time in which such work operations are carried out with the splitting wedge uninstalled.
An object of the exemplary embodiments and/or exemplary methods of the present invention, therefore, is to provide a circular saw with an alternative design which at least partially eliminates the previously described problems and disadvantages.